In recent years, a device that detects a rotation angle of a rotary shaft has been suggested.
For example, Patent Literature 1 describes a rotation angle detection device having a following configuration. Specifically, the rotation angle detection device described in Patent Literature 1 is a rotation angle detection device including: a magnetic rotor having a bipolar magnet; and a sensing device that senses a direction of magnetic flux from the magnetic rotor. The sensing device has a magnetically sensitive surface configured with plural magnetoresistance effect elements, and is provided with respect to the magnetic rotor such that the magnetic flux is intersected with the magnetically sensitive surface and magnitudes of amplitudes of the magnetic flux density components orthogonal to each other in the magnetically sensitive surface are equal to each other.